8808A 
Users Manual 
4-10 
Note 
In external trigger mode (mode 2 to mode 5), *TRG command is always 
available. 
Setting the Trigger Type Configuration 
To set the trigger type configuration using the computer interface, enter the command 
TRIGGER <type> (where <type> is the trigger type) and press Enter. See Table 4-3 for 
trigger types. 
Select trigger type 3 or 5 to enable the settling delay if the input signal is not stable before 
a measurement is triggered. Typical settling delays are provided in Table 4-3. RS-232 
reading transfer rates are provided in Table 4-4. 
Table 4-4. RS-232 Reading Transfer Rates 
Readings per Second 
Rate 
Internal Trigger Operation (Trigger 1)  External Trigger Operation (Trigger 4) 
Slow 2.5
[1]
 2.5
[2]
 
Medium 20
[1]
 20
[2]
 
Fast 100
[1]
 100
[2]
 
[1]  Depends on A/D trigger speed. 
[2]  Depends on how fast the trigger signal is transmitted.
 
External Trigger via the Computer Interface 
To trigger a measurement using the RS-232 computer interface, enter the command 
*TRG and press Enter. See the “Common Commands” section later in this chapter for use 
of *TRG command. 
To trigger a measurement using pin 9 of the RS-232 interface, see Figure 4-1. 
+5 V Out (Pin 1)
Trig In (Pin 9)
 
eue24.eps 
Figure 4-1. External Trigger Using Pin 9 of RS-232 Interface 
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